If you've ever received newsletters or brochures in the mail, chances are they were held together by wafer seals. They are are self-adhesive paper disks used to prepare self-mailing materials for delivery or to seal envelopes securely without glue. Some wafer seals are perforated to prevent damage while opening, while others may be serrated for decoration or embossed for personalization. Many stamp collectors also have an interest in certain vintage or historic seals.
The use of wafer seals for envelopes and self-mailing documents was most likely derived from the earlier practice of using wax seals. Official wafer seals could also be commissioned in order to verify the authenticity of a decree or military order. Any hint of tampering or unauthorized reading could be detected by examining the seals. It is these elaborate versions that most interest stamp collectors today. As other forms of document protection, such as the self-sealing envelope, became more common, the use of official wafer seals declined. The practice is now mostly used during ceremonies or as official seals on formal invitations.
Today, most wafer seals are sold on rolls through office supply stores and party shops. The more generic versions may also be called mailing tabs. Their main functions are to seal self-mailing newsletters and other bulky brochures and to provide a decorative seal for envelopes.
Changes in the postal system have resulted in an increased need for mailing tabs. Folded newsletters and other self-mailers can no longer be sealed with metal staples. The approved solution is to use one or two wafer seals along the bottom or top edge of the folded material for security. The seals must be placed in specific areas, usually near the edges, so they do not block any official mailing bar codes or address information.
Wafer seals come in a variety of styles and colors, from utilitarian butterfly tabs to elaborately embossed invitation seals. Some are clear in color, while others can be shiny or metallic. There are also versions suitable for specific holidays or other occasions.